In the array below, in how many different ways can we start with the letter A and move from letter to letter (horizontally, vertically, or diagonally), to spell the word "ARCH"?

To start with the letter A and move horizontally, vertically, or diagonally to spell the word "ARCH" in the given array, we can consider the following paths:

Path 1: A -> B -> H -> C
Path 2: A -> B -> C -> H
Path 3: A -> G -> F -> C -> H
Path 4: A -> H -> C -> G
Path 5: A -> H -> G -> F -> C

Therefore, there are 5 different ways we can start with the letter A and move to spell the word "ARCH".

To find out the number of different ways we can spell the word "ARCH" starting from the letter A and moving horizontally, vertically, or diagonally in the given array, we will step-by-step determine all the possible paths.

Array:
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X Y

Step 1: Start at the letter A
A

Step 2: Move to neighboring letters
We can move to the following neighboring letters from A: B, F, G

A - B
|
F

A - B - C
| |
F G

Step 3: Move to neighboring letters
From C, we can move to the following neighboring letters: G, K, L, D

A - B - C - G
| | |
F L D

A - B - C - G
| | |
F K D

Step 4: Move to neighboring letters
From G, there are no valid neighboring letters for the next step.

A - B - C - G

Step 5: Move to neighboring letters
From L, we can move to the following neighboring letters: H, M, Q

A - B - C - G
| | |
F L - H
|
M

A - B - C - G
| | |
F L - H
|
Q

Step 6: Move to neighboring letters
From H, we can move to the following neighboring letters: M, Q, R

A - B - C - G
| | |
F L - H - M

A - B - C - G
| | |
F L - H - Q

A - B - C - G
| | |
F L - H - Q - R

Step 7: Move to neighboring letters
From Q, there are no valid neighboring letters for the next step.

A - B - C - G
| | |
F L - H - Q

Step 8: Move to neighboring letters
From M, we can move to the following neighboring letters: I, N

A - B - C - G
| | |
F L - H - M - I

A - B - C - G
| | |
F L - H - M - N

Step 9: Move to neighboring letters
From I, there are no valid neighboring letters for the next step.

A - B - C - G
| | |
F L - H - M - I

Step 10: Move to neighboring letters
From N, we can move to the following neighboring letters: O, S

A - B - C - G
| | |
F L - H - M - N - O

A - B - C - G
| | |
F L - H - M - N - S

Step 11: Move to neighboring letters
From O, there are no valid neighboring letters for the next step.

A - B - C - G
| | |
F L - H - M - N - O

Step 12: Move to neighboring letters
From S, we can move to the following neighboring letters: T

A - B - C - G
| | |
F L - H - M - N - S - T

So, by traversing through the given array and following all the possible paths, we have found 12 different ways to spell the word "ARCH" starting from the letter A and moving horizontally, vertically, or diagonally.